git-publish: use sub-command symbolic-ref to find branch name
git-publish: use sub-command symbolic-ref to find branch name

Instead of relying on human formatted output to figure out the currently
checkout out branch. Instead use the symbolic-ref command available
since v0.99 to determine the name of 'HEAD'.

Signed-off-by: Jonathan Toppins <d37c3608bdaa3ffecc3bffd396174be8f24f61bc@redhat.com>
Signed-off-by: Stefan Hajnoczi <484520986196e4a799496429ce8a499eb6488adb@gmail.com>

stefanha/git-publish,stefanha/git-publish